±15kV ESD-Protected, +5V RS-232 Transceivers
MAX202E–MAX213E, MAX232E/MAX241E
R
C
1MΩ
CHARGE-CURRENT-
LIMIT RESISTOR
HIGH-
VOLTAGE
DC
SOURCE
R
D
1500Ω
DISCHARGE
RESISTANCE
DEVICE
UNDER
TEST
I
P
100%
90%
AMPERES
36.8%
10%
0
0
t
RL
TIME
Ir
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
Cs
100pF
STORAGE
CAPACITOR
t
DL
CURRENT WAVEFORM
Figure 6a. Human Body ESD Test Model
Figure 6b. Human Body Model Current Waveform
I
R
C
50MΩ to 100MΩ
CHARGE-CURRENT-
LIMIT RESISTOR
HIGH-
VOLTAGE
DC
SOURCE
R
D
330Ω
DISCHARGE
RESISTANCE
DEVICE
UNDER
TEST
100%
90%
Cs
150pF
STORAGE
CAPACITOR
I
PEAK
10%
Figure 7a. IEC1000-4-2 ESD Test Model
t r = 0.7ns to 1ns
t
30ns
60ns
IEC1000-4-2
The IEC1000-4-2 standard covers ESD testing and
performance of finished equipment; it does not
specifically refer to integrated circuits. The
MAX202E/MAX203E–MAX213E, MAX232E/MAX241E
help you design equipment that meets level 4 (the
highest level) of IEC1000-4-2, without the need for
additional ESD-protection components.
The major difference between tests done using the
Human Body Model and IEC1000-4-2 is higher peak
current in IEC1000-4-2, because series resistance is
lower in the IEC1000-4-2 model. Hence, the ESD
withstand voltage measured to IEC1000-4-2 is
generally lower than that measured using the Human
Body Model. Figure 7b shows the current waveform for
the 8kV IEC1000-4-2 level-four ESD contact-discharge
test.
12
Figure 7b. IEC1000-4-2 ESD Generator Current Waveform
The air-gap test involves approaching the device with a
charged probe. The contact-discharge method
connects the probe to the device before the probe is
energized.
Machine Model
The Machine Model for ESD tests all pins using a
200pF storage capacitor and zero discharge
resistance. Its objective is to emulate the stress caused
by contact that occurs with handling and assembly
during manufacturing. Of course, all pins require this
protection during manufacturing, not just RS-232 inputs
and outputs. Therefore, after PC board assembly, the
Machine Model is less relevant to I/O ports.
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